In the world of drug dealing, usually a group of individuals who make their living setting up and then robbing unsuspecting hustlers. Can rob by force or wits, either way a force to be avoided. Sure signs are guns, excessive talk and lies, large groups of similarly dressed/similar looking people involved in a transaction.

Couple of jackers shot out my back window last night when I sped out of their set-up.

The Urban Dictionary T-Shirt

jacker-a man or womans career choice in the street game ,a jacker is somebody who will take ur shoes by verbal commands,threats,violence,a person who commits robbery on others wich in terms of the street instead of a robber its a jacker.one who holds repuatation for jackin everything,i mean everything thats a real jacker

jacker-bruh when i see him on the outs ,ima jack his whole crew, cellmate-bruh u is in here for jackin

The Urban Dictionary T-Shirt

A female, who often goes by the name Lauren, who enjoys taking objects, mostly straightedges, from their Geometry partners. They are often seen yelling and looking for their protractor, realizing it is gone, and jacking someone else's. They have serious problems.

Lauren is such a jacker because she enjoys stealing objects of the straightedge type.